The role of phase

This demonstration (you can watch a video there) comes from Harvard Natural Sciences Lecture Demonstrations

What it shows: Fifteen uncoupled simple pendulums of monotonically increasing lengths dance together to produce visual traveling waves, standing waves, beating, and random motion. One might call this kinetic art and the choreography of the dance of the pendulums is stunning! Aliasing and quantum revival can also be shown.

How it works: The period of one complete cycle of the dance is 60 seconds. The length of the longest pendulum has been adjusted so that it executes 51 oscillations in this 60 second period. The length of each successive shorter pendulum is carefully adjusted so that it executes one additional oscillation in this period. Thus, the 15th pendulum (shortest) undergoes 65 oscillations. When all 15 pendulums are started together, they quickly fall out of sync—their relative phases continuously change because of their different periods of oscillation. However, after 60 seconds they will all have executed an integral number of oscillations and be back in sync again at that instant, ready to repeat the dance.

Graphene age

In the past 20 years, we have gone through the copper age and iron age, both in superconductivity, weighing in strongly correlated systems. Some people might even have an impression that, few new physics can be found outside the U-regime. U is the Hubbard repulsion. But imagination leads us beyond that sight: we have found surprises and fostered new cherished babies in the usual band theory. We now are digging in the topological insulators and graphene, which are constantly offering exotic and practically important physics. The lesson here is: imagination is more important than knowledge ! (Einstein)

News from this issue of Science Magazine

1. Batteries are going to break out from old forms:

Now he's on his way. Last month, Chiang and his colleagues reported in Advanced Energy Materials that they've created a new battery design called a semisolid flow cell that's like a battery with a fuel tank. Like today's batteries, the device contains lithium ions that shuttle back and forth either storing or releasing electrical charges on demand. But instead of packaging those ions along with the electrodes and other apparatus all together, as in a typical battery, Chiang's semisolid flow cell separates the energy-delivery apparatus from energy storage. In this battery, the storage medium is a pair of gooey, black liquids, the consistency of yogurt, that contain nanoscale particles of materials commonly used as anodes and cathodes in lithium-ion cells. These particles are suspended in an electrolyte and separated by a porous membrane. When power is needed, a bolus of each goo is pumped from external tanks into a network of current collectors that extract electrons while lithium ions shuttle through the membrane from the anode particles to the cathode particles. The spent slurries can then be reenergized, as in a normal rechargeable battery, or pumped out and replaced. Other types of flow batteries have been made in the past, but Chiang says the new setup can store up to 30 times as much energy as previous versions. He has launched another company, called 24M, to commercialize the technology.[http://www.sciencemag.org/content/332/6037/1494.full]

2.

Move over, China. Japan's “K Computer” is now the fastest supercomputer in the world. On 20 June, K was ranked number one in the TOP500 list of the world's supercomputers, performing three times as fast as its Chinese rival and the previous champion, Tianhe-1A.

The TOP500 list is updated twice a year and ranks how quickly computers solve a standard mathematical equation. K, built by Fujitsu and located at the RIKEN Advanced Institute for Computational Science in Kobe, can perform 8.2 quadrillion calculations per second, equivalent to linking about 1 million desktop computers. That performance is still shy of the target kei, or 10 quadrillion, calculations for which the supercomputer was named. This is the first time Japan has topped the list since 2004.[http://www.sciencemag.org/content/332/6037/1488.2.full]

3. Education is not a rece:

In the United States and elsewhere, the competitive pressures placed on young people in school are damaging many otherwise promising lives. In addition to generating debilitating anxiety and encouraging a culture of cheating, this competition takes the joy out of learning. The film Race to Nowhere, which continues to receive attention since its release a year ago, documents the unhealthy consequences of the competitive “teach to the test” climate that many U.S. students experience. The film, in which I was interviewed, puts in clear relief the pressures that youth are under to amass large numbers of Advanced Placement (college-equivalent) classes, win science fairs, excel in the arts and sports, and in other ways distinguish themselves from the competition for admission into a few select universities that parents and schools believe are critical for future success. Research on motivation makes it clear that focusing attention entirely on performance, whether grades or test scores, destroys whatever intrinsic interest the subject matter might have had.* There are certainly students whose passions spur them to realize their full potential in rigorous academic courses and other impressive activities. But how many potential Nobel Prize winners have written off science before the end of high school because their only exposure to the subject had been in test preparation courses rather than in classes that delved into meaningful questions? It doesn't have to be this way, but change will require coordinated efforts at many levels.

Success in life does not require a degree from one of 10 universities. We need to evaluate U.S. high schools (pre-college education) on how well they help students find a college that matches their interests and goals, not on the proportion of students that they send to elite institutions. And the coveted universities need to demonstrate that they are interested in students who have a genuine passion for extending their educational experience, not merely in tallying items on resumés.

Many U.S. teachers also must change their approach to teaching. Extensive research shows that students will become more emotionally engaged (and even passionate) if simple principles are followed: if the subject matter is connected to students' personal lives and interests; if students have opportunities to be actively involved in solving or designing solutions to novel and multidimensional problems, doing experiments, debating the implications of findings, or working collaboratively; if students have multiple opportunities to earn a good grade (by rewriting papers or retaking tests); if attention is drawn to the knowledge and skills that students are developing, not to grades or scores; and if all learning and skill development is celebrated, whatever the level.

Schools must create homework policies to ensure that diligent students aren't kept up late into the night; schedule some spacing between major tests and offer ample opportunities for students to get extra help; make sure that at least one adult is paying attention to every student's emotional needs; provide parent education on the advantages of a broad array of potential colleges; survey students regularly on the sources of their stress and make sure that this feedback informs policies; and offer opportunities for students to pursue academic interests unencumbered by performance concerns, such as in independent studies or clubs.

The world is rapidly changing. Problem-solving skills and critical analysis have become infinitely more important than being able to answer the typical questions given on standardized tests. A valuable science of teaching and learning exists that should guide efforts to improve students' interest, engagement, and intellectual skills, as well as reduce the debilitating stress that is becoming epidemic.** Only by paying attention to what we know can we make the changes that youth need to lead healthy and productive lives. [http://www.sciencemag.org/content/332/6037/1481.full]

Physics Education Journal

I like this journal very much ! It is nice, filled with wonderful and provoking 'mundane' experiments ! I love finding out the physics behind these 'mundane' things and puzzles. That is really something that can easily occupy my mind. I love them, to say it again! I will use it to educate my children, Aha !
http://iopscience.iop.org/0031-9120/

Singapore strengthes its science

As a small country, it has made really amazing progress in science and technology.
http://ptonline.aip.org/journals/doc/PHTOAD-ft/vol_64/iss_6/20_1.shtml?type=PTALERT

A tutorial on band structure calculation

I have encountered some Phd in physics who even could not calculate band structure ! So, I would like to recommend the following paper (which is brought to my attention thanks to Zapper's blog) to all those avid to know this technique: http://arxiv.org/PS_cache/arxiv/pdf/1105/1105.0220v1.pdf

A TED talk by Janna Levin

I would like to embed the link to her talk. In this film, she talks of black holes , dynamics of space-time in the form of gravitational waves and the big bang. Especially, she discusses how such things can be heard. She presented to audience some astounding examples. I'm really impressed in the wonders of the pictures she brought there. They were actually made by numerical simulations.
That is marvelous !

What happend at the Fukushima reactor ?

The 9.0 level earthquake took place in Japan and caused damage to the nuclear reactors. Now the media are disseminating and making up all kinds of bells and whistles around a possible disaster like Chernobly catastrophe. And the mass and some activists rise to protest against nuclear plants plan. So, the earnest question is, is the nuclear industry really so unsafe ? Here is an excellent article speaking of this. His view is that, the event in Japan witnessed the success of the modern technology, rather than a failure that is spread so widely in the media.

As a nuclear engineer, it is depressing to read the recent reports on the Fukushima nuclear incident — not because of the incident itself (at this point I strongly believe that we will remember Fukushima as evidence of how safe nuclear power is when done right) — but because the media coverage of the event has been rife with errors so glaring that I have to wonder if anyone in the world of journalism has ever taken a physics class. My favorite: in one article, boric acid was described as a “nutrient absorber” instead of a “neutron absorber.” How many editors signed off on that line without asking, “Why would a nuclear reactor need to absorb nutrients?”

Whether it is confusion of radiation with radioactive material, flailing comparisons to past accidents, or hopeless misuse of terminology, reporting on Fukushima has been a mix of hype and speculation entirely devoid of useful information. Let’s set the record straight: the situation is under control, it is unlikely that the nuclear fuel has melted, the risk to the public is effectively zero, and, depending on whether facts on the ground have been reported correctly, it is possible that the reactors will remain capable of producing power in the future.

Postdocs structured into a new permenent post ?

She thinks so:
" The scientific enterprise is run on what economists call the 'tournament' model, with practitioners pitted against one another in bitter pursuit of a very rare prize. Given that cheap and disposable trainees — PhD students and postdocs — fuel the entire scientific research enterprise, it is not surprising that few inside the system seem interested in change. A system complicit in this sort of exploitation is at best indifferent and at worst cruel. I have no doubt that most lab heads want the best for their many apprentices, but at the system level, the practice continues. Few academics could afford to warn trainees against entering the ring — if they frightened away their labour force, research would grind to a halt.

An alternative career structure within science that professionalizes mature postdocs would be better. Permanent research staff positions could be generated and filled with talented and experienced postdocs who do not want to, or cannot, lead a research team — a job that, after all, requires a different skill set. Every academic lab could employ a few of these staff along with a reduced number of trainees. Although the permanent staff would cost more, there would be fewer needed: a researcher with 10–20 years experience is probably at least twice as efficient as a green trainee. Academic labs could thus become smaller, streamlined and more efficient. The slightly fewer trainees in the pool would work in the knowledge that their career prospects are brighter, and that the system that trains them wants to nurture them, not suck them dry and spit them out. "[http://www.nature.com/news/2011/110302/full/471007a.html?WT.ec_id=NATURE-20110303]

Henry's design was found an error

This interesting study has acquired attention from Nature Physics. The authors reveal an error with Henry's design on display in Princeton University.

In 1831, Henry invented a battery-powered rocking-beam motor that he later described as the first electromagnetic machine. He repeatedly modified the design over his career, but only one version of a motor actually constructed by Henry is known to exist. This version is in a collection of Henry instruments at Princeton University. We found that the Princeton motor cannot have operated in the
form that was displayed as early as 1884. We found evidence in several historical documents and in the instrument itself that the field magnet shown with the motor is a mistake. Instead of a single horizontal bar magnet, the motor was designed to use two elliptical magnets. We presume the error was made by whoever assembled the first public display. We modeled the dynamics of Henry’s vibrating motor and compared our results to the operation of a replica motor. Modeling provides
insight into how the motor is able to vibrate indefinitely even in the presence of energy loss due to friction. © 2011 American Association of Physics Teachers.
DOI: 10.1119/1.3531940

flaming tornado

It is always a pleasure to watch simple but 'wonder' provoking experiments like this one. It plays with flames. Places some fuel in a plate and ignite it and then trap it with a web cage. Now you spin the cage, and you'll see the flames grow tall and thin into a flame tornado. Ever wondered why ? It is actually easy to explain. Try it yourself. Cool !

How do you get yourself less wet if you are caught in a rain ?

This is a daily problem and is funny enough and thus deserves a journal paper [Eur. J. Phys. v.32, p.355 (2011)] to deal with it. Unfortunately, I could not say more, as I'm not able to access it freely. Only the abstract is posted: "The question whether to walk slowly or to run when it starts raining in order to stay as dry as possible has been considered for many years—and with different results, depending on the assumptions made and the mathematical descriptions for the situation. Because of the practical meaning for real life and the inconsistent results depending on the chosen parameters, this problem is well suited to undergraduate students learning to decide which parameters are important and choosing reasonable values to describe a physical problem. Dealing with physical parameters is still useful at university level, as students do not always recognize the connection between pure numbers and their qualitative and quantitative influence on a physical problem. This paper presents an intuitive approach which offers the additional advantage of being more detailed, allowing for more parameters to be tested than the simple models proposed in most other publications."

Time for Scientists to underpin Wikipedia

Wikipedia, the world's largest online encyclopaedia, is regarded with suspicion by some in the scientific community — perhaps because the wiki model is inconsistent with traditional academic scholarship (Nature 468, 359–360; 2010). But the time has come for scientists to engage more actively with Wikipedia.

Type any scientific term into any search engine and it is likely that a Wikipedia article will be the first hit. Ten years ago, it would have been inconceivable that a free collaborative website, written and maintained by volunteers, would dominate the global provision of knowledge. But Wikipedia is now the first port of call for people seeking information on subjects that include scientific topics. Like it or not, other scientists and the public are using it to get an overview of your specialist area.

Wikipedia's user-friendly global reach offers an unprecedented opportunity for public engagement with science. Scientists who receive public or charitable funding should therefore seize the opportunity to make sure that Wikipedia articles are understandable, scientifically accurate, well sourced and up-to-date.

Many in the scientific community will admit to using Wikipedia occasionally, yet few have contributed content. For society's sake, scientists must overcome their reluctance to embrace this resource. [Nature, 468:765]

Wikipedia goes to Grad

Science, Volume 330, Number 6006, Issue of 12 November 2010:

Education:

Wikipedia Goes to Grad School

Melissa McCartney

Very few graduate-level science curricula include training in communicating advanced concepts to a general audience. Moy et al. report a class project that addressed this by having chemistry students edit an entry in Wikipedia.org collaboratively. Students selected topics that were related to the course and were minimally covered on Wikipedia. Student entries contained references, an introduction aimed at the general public, and figures to enhance the explanation of the topic. Student feedback collected at the end of the project revealed increased knowledge of their topic. A specialist in writing and rhetoric concluded that the students' entries were more engaging to general readers because of the attention to real-world applications and clear explanations of vocabulary. Course professors noted that students appeared to assess the material they added to the entry more critically than when they were simply studying for the class, which is consistent with the notion of students' developing a higher level of explanatory knowledge when teaching the material is a goal.

J. Chem. Educ. 87, 1159 (2010).

The physics in skateboarding

Here is a video that talks about how to improve skateboarding tricks by the help of simple physics,
especially the so-called "Ollie":
http://www.sciencedaily.com/videos/2007/0701-science_of_skateboarding.htm

The Theoretical Group As Founded

It is a pleasure to announce that, with some friends I have founded a theoretical group of physics in Hong Kong. This is a very small one, resembling the Olympia Academy and intended for very motivated young peers to communicate their scientific activities. The meeting is on every Tuesday and informal. No money is needed to run this. All are just like minds. Basically, we

(1) Invite peers to present their latest studies or something they find stunning and then discuss the topics;
(2) Learn some new topics through a presentation by one of the participants.

I must say, the presentations are really very theoretical and contain many difficult math. So, we are indeed serious in doing this.

Cloud Chamber

A cloud chamber (CC) is used to detect tiny radiation particles. It was invented by Wilson and won him a Nobel Prize. The operating principle is simple: soak a chamber with alcohol and then seal it, and cool it down. The supercooled air shall enter a metastable state but the alcohol evaporation get ready to condense, which can be ignited by a small perturbation (nucleation centers). When a particle passes through this chamber, liquid drops shall track it and make it detectable.

This is a Video demonstrating how to make a simple cloud chamber:
http://education.jlab.org/frost/cloud_chamber.html

Note: a metastable state is a state that is stable but not robust against any perturbations.

comic physics

Don't let yourself miss this funny stuff !

Failed theories of SC

In one of my previous entries, I mentioned the failed theories that were briefly reviewed in a preprint. Here in Nature Physics [Nature Physics, 6: 715, 2010], another one based on this review came out. I especially like this story about Laudau:

Yet it turns out that Landau first proposed these ideas in the context of superconductivity, thinking not of magnetization but of electrical current. He expanded the free energy F around the state of zero current, j = 0, and argued that as the direction of the current shouldn't affect F, the odd terms should vanish. This gives an equation of the form F(j) = F(0) + aj² + bj⁴. Assuming b > 0 and that a passes through zero at a critical temperature T_c, he showed that there could be an abrupt transition from zero to non-zero current below T_c.

This early theory conflicted with observations — it erroneously predicted j ~ (T_c − T)^1/2 just below the critical temperature — and Landau went back to the drawing board. Yet here already were the seeds of the later Ginzburg–Landau theory of phase transitions. And Landau's introduction of the notion of an 'order parameter' as a convenient handle on order and how it changes has influenced physics ever since, even if it did appear in a failed theory.

This idea is crazy: when one expands free energy in current, one has in his mind that he is dealing with an equilibrium state. However, current usually exists in a non-equilibrium state. This gives a glimpse of the aberration of superconductivity !

Scientists need a shorter path to research freedom

Usually a young needs to go through all the stages to arrive at its final intellectual autonomy, from undergrad, to PhD (sometimes even Mphil beforehand), and postdoc training. All these may take him around 15 years, which is very long and too long for the most gifted young who are highly creative and confident and motivated. Full pursuit freedom is quite essential to astounding ingenious findings. Einstein is the example. He acquired his independence by his uncompromisable desire for intellectual liberty and unbounded curiosity. Nothing could stop him from his zealous investigation. However, not all have his luck: he is with a incredibly strong heart that stems from his unfathomable passion and could overcome any balk ahead. Many young are talented but somewhat not that talented. They need a smoother academic environment to release their energy, or they would be throttled.

Nature 467, 635 (2010)

Over the past half-century, a great many things have changed in biomedical research. Along the way, postdoctoral training has become an established step in a research career. But this development has proved a double-edged sword for some — and possibly for the whole field.

Without question, postdoctoral training has enriched the experience of many by allowing protected time for full immersion in research. Postdocs provide essential skills and serve as first authors on many important papers, thus boosting research productivity. But these gains must be set against the significantly longer time it now takes for most young scientists to launch independent research careers. The average age of PhD scientists awarded their first research grant from the US National Institutes of Health (NIH) last year was 42. In 1981, the average was 36. As director of the NIH, I believe this is a problem that should be addressed. We must develop ways to liberate our brightest minds to pursue high-risk, high-reward ideas during their most creative years.

There are many complex reasons for the increased training periods, including an academic culture that emphasizes the need for longer, sometimes multiple, postdoc positions to build a stellar CV. There is a shortage of faculty vacancies, and institutions often insist that recruits win independent funding before appointing them to tenure-track posts. And there is too little emphasis on alternative scientific careers, such as industry, law, teaching and policy.

Many young researchers baulk at the prospect of such an extended period of limited intellectual autonomy. It is also a concern to veterans such as myself. I fear that science may be suffering because of a failure to encourage the independence of the next generation of great minds.

My own pathway to independence involved a three-year postdoctoral fellowship in human genetics in the lab of Sherman Weissman at Yale School of Medicine in New Haven, Connecticut. I was fortunate to be mentored by an adviser who encouraged autonomy and creativity. I used the opportunity to develop an innovative approach, called chromosome jumping, for crossing large strands of DNA to identify genes responsible for inherited disorders. It was a good launching pad; I received my first R01 grant from the NIH at age 34, the same year I began a faculty position at the University of Michigan in Ann Arbor.

In my lab at the NIH, I strive to cultivate the independence of young scientists as early as possible. One of my strategies is to assign new recruits a 'thinking period' devoted to formulating project ideas. Through an iterative process involving myself and the recruit, we refine the research direction until we have settled on a good fit. I think this strategy has worked well in encouraging forward thinking, but it may still be a halfway solution. For the most creative of young scientists, nothing can equal the chance to have a lab of one's own.

To provide such opportunities, several programmes aimed at promoting greater independence at earlier career stages have sprung up over the years, producing some spectacular investigators. And so, after much consultation with outside advisers, the NIH this week launched its own effort, the Early Independence Award Program (see http://go.nature.com/nFqYE5), which will initially support ten creative young scientists to pass almost immediately from completing a PhD to running their own laboratories. The awards will be paid by the NIH Director's Common Fund and administered through a peer-reviewed application process, supporting an investigator at a level of US$250,000 in direct costs per year for five years — the equivalent of a standard NIH R01 grant.

Unlike many similar programmes, the awards will give students flexibility to seek a position at any suitable institution. Applicants will need to work with the institution's academic leaders to negotiate an independent position that would be activated if they win an award. We hope that department heads will find this an attractive tool for recruiting talent to invigorate their institution's research environment. For its part, the institution must provide the young investigator with space and resources, and a level of mentoring equivalent to that provided to assistant professors.

I am aware that many speed bumps may lie on this expressway to independence. The programme requires highly motivated and mature applicants who are talented and confident enough to launch their own research programme and negotiate support from a department chair. And it requires institutions willing to support an award winner who will be unusually young in their career. The pilot programme, which we expect to be highly competitive, will issue its first awards next year. Although not intended to replace traditional postdoctoral training, the pilot can be scaled up if successful.

This programme is not for everyone, and postdoctoral positions will continue to expand the skills and experience of most young scientists. But for exceptional individuals with the intellectual and experimental sophistication to initiate an independent career at the end of doctoral training, this programme will provide the opportunity. I have been involved in the launch of many pilots, including that of the Human Genome Project, but I have a special affinity for this one: the future of biomedical research relies on the creativity and energy of its investigators. Unleashing that capability at all stages of a scientist's career should be a priority for us all.

Francis Collins is director of the US National Institutes of Health. e-mail: francis.collins@nih.gov